1. Field of the Invention
This invention relates, generally, to reclamation of thin films. More particularly, it relates to the reclamation of heavy metals that are present in photovoltaic cells and to edge deletion of said heavy metals from photovoltaic cells.
2. Description of the Prior Art
U.S. Pat. No. 6,391,165 to Bohland et al. discloses a means of crushing and separating the various components of a solar panel to extract the heavy metals for reclamation with subsequent chemical etching and separation. The disclosed means does not prevent the toxic materials from becoming airborne and the process requires hazardous materials to separate the heavy metals.
U.S. Pat. Nos. 5,897,685 and 5,997,718 to Goozner et al. disclose acids to reclaim heavy metals from thin film solar panels. The use of such chemicals is a toxic process.
U.S. Pat. No. 6,572,782 discloses a method in which solar panels are mechanically disintegrated and then exposed to an oxygen atmosphere at high temperatures (300° C.) to achieve a gaseous decomposition. A subsequent exposure to chlorine gas at 400° C. forms CdCl2 and TeCl4 which condense and precipitate by cooling.
Sand blasting reclamation is also well-known but the reclamation of heavy metals or toxic materials from the sand is not easy. Moreover, the sand itself becomes toxic waste and must be disposed of as such. Sand is further used as a means to edge delete a solar panel to permit hermetic sealing of the panel from the elements. The sand can get onto the panel and damage the sensitive photovoltaic layers. Lasers are also used to edge delete but the material containing heavy metal materials become an airborne hazard in the surrounding environment.
U.S. Pat. Nos. 5,637,245, 6,407,385, 6,419,996, and 6,777,642 disclose methods for cleaning materials with a laser and liquid. None of the disclosed methods provide a safer means of extracting the heavy metals and accommodating the size of a solar panel.
However, at the time the present invention was made, it was not obvious to those of ordinary skill in view of the prior art considered as a whole how the reclamation and edge deletion process could be improved.